Blotchiness in 1.50 SP1

[nate]

Once again I am perplexed by Vray!

I've attached an image which is a high-res render. The model is currently using only plain white Vray mats and Vray plane lights but has all this terrible noise and blotchiness. (I've upped the contrast slightlly in photoshop so the problem is more obvious).

I have the same problem with another model that I've been working on that has all the materials in place as well as photometric lights and vray lights so I know it must be something I'm doing with the settings but I have no idea what? I haven't had this before in any of the visuals that I've done so it's unchartered territory.

Nothing is coming up in the vray log, settings are attached.

I've tried upping the HSph subdivs and interp. samples but this didn't clear the blotchiness of the image.

Anyone had this before?

[vlado]

Do you have overlapping faces on your geometry?

Best regards,
Vlado

[Shane W]

Try changing your irradiance map interpolation to least squares fit and see if that helps.

-Shane

[vlado]

Ah, yes, I missed this; try the least squares interpolation and also increase your hemispheric subdivs, 40 is too low for this kind of scene.

Best regards,
Vlado

[nate]

I didn't think it would be that easy (then again, based on previous experience!) but that seems to have done the trick! I might actually get to go on my christmas holiday after all

Could either of you quickly outline for me why this interpolation type works better? Or what is it in a scene that demands a different interpolation type? For example, delone works best for glossy scenes or whatever, or is it just trial and error?

Thanks again for your help, this forum is a life saver when you've still got so much to learn.

[vlado]

Well, I would not recommend to use the delauney triangulation as a rule; the default is the least-squares interpolation and it works very well in many cases. Since it uses more samples to interpolate over, it is able to produce a much smoother result than the delauney one.

Best regards,
Vlado

[nate]

Thanks for explaining that Vlado. By switching over to least squares and upping the subdivs to 60 the blotchiness disappears but reflective surfaces are really noisy.

I've tried changing the sample look up and increasing the interp. samples but this hasn't made a difference, would this be something to do with the settings on the DMC sampler?

[nate]

I've just realised that the reflections get noiser the further away from the camera an object is. So the floor has sharp reflections by the camera which get progressively noisier moving away?

[Clifton Santiago]

You would need to post an image with these reflective surfaces to which you refer. Are these reflective surfaces glossy? If so, what is your subdivs for your reflective glossies?Try turning it up to 24. If still "noisy" try increasing your subdivs multiplier. I usually set mine at 8 for finals. If these settings slow things down, use LC for secondary bounces and select use LC for glossies option to accelerate.

[nate]

The refelctive surfaces are glossy but increasing the reflective subdivs to 24 didn't make any difference. LC for glossies option ticked and taking DMC sampler noise threshhold from 0.005 to 0.001 haven't worked either.

Here's the furthest part of the shot, the lift doors should be stainless and the TV screen should just be refelctive 'switched off' screen but all I'm getting is this noise?

[Clifton Santiago]

Dude, I can't see anything in that little picture. Turning down your noise size is not the issue, that just slows things down. My noise size is at 0.01 and I never have visible noise. You need to increase your glossy subdivs to 24 and turn up your subdivs multiplier to 8.

[nate]

Thanks Clifton, I did what you said (global subdivs to 8, right?) and it worked a treat. I'm just working on bringing the subdivs down incrementally now to try and lower the render time without comprimising the quality.

[Clifton Santiago]

Yep, thats right. Yeah, the settings I gave you are final settings, though I use them for drafts now that I have about 30 cores on render nodes for DR. My settings are faster than the "universal settings" though...

[nate]

Hmm, makes my 3 render nodes look measly